Free-space optical channel estimation for physical layer security

TL;DR

This paper experimentally investigates free-space optical channels for physical layer security, analyzing channel metrics and proposing a multi-layer security approach for satellite-to-ground laser communications.

Contribution

It provides experimental data and analysis of FSO channel metrics for security, and offers guidelines for combining PHY and upper-layer security strategies.

Findings

Estimated secrecy rate and outage probability under realistic fading.

Demonstrated secure message transmission in FSO links.

Proposed multi-layer security architecture for satellite communications.

Abstract

We present experimental data on message transmission in a free-space optical (FSO) link at an eye-safe wavelength, using a testbed consisting of one sender and two receiver terminals, where the latter two are a legitimate receiver and an eavesdropper. The testbed allows us to emulate a typical scenario of physical-layer (PHY) security such as satellite-to-ground laser communications. We estimate information-theoretic metrics including secrecy rate, secrecy outage probability, and expected code lengths for given secrecy criteria based on observed channel statistics. We then discuss operation principles of secure message transmission under realistic fading conditions, and provide a guideline on a multi-layer security architecture by combining PHY security and upper-layer (algorithmic) security.